<template>
  <div class="app-container">
    <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息" />
      <el-step title="创建课程大纲" />
      <el-step title="最终发布" />
    </el-steps>

    <el-form label-width="120px">
      <el-form-item label="课程标题">
        <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写" />
      </el-form-item>

      <!-- 所属分类 TODO -->
      <el-form-item label="课程分类">
        <el-select
          v-model="courseInfo.subjectParentId"
          placeholder="一级分类"
          @change="subjectLevelOneChanged"
        >
          <el-option
            v-for="subject in subjectOneList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"
          />
        </el-select>

        <!-- 二级分类 -->
        <el-select v-model="courseInfo.subjectId" placeholder="二级分类">
          <el-option
            v-for="subject in subjectTwoList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"
          />
        </el-select>
      </el-form-item>

      <!-- 课程讲师 TODO -->
      <!-- 课程讲师 -->
      <el-form-item label="课程讲师">
        <el-select v-model="courseInfo.teacherId" placeholder="请选择">
          <el-option
            v-for="teacher in teacherList"
            :key="teacher.id"
            :label="teacher.name"
            :value="teacher.id"
          />
        </el-select>
      </el-form-item>

      <el-form-item label="总课时">
        <el-input-number
          :min="0"
          v-model="courseInfo.lessonNum"
          controls-position="right"
          placeholder="请填写课程的总课时数"
        />
      </el-form-item>

      <!-- 课程简介-->
      <el-form-item label="课程简介">
        <tinymce :height="300" v-model="courseInfo.description" />
      </el-form-item>

      <!-- 课程封面 TODO -->
      <!-- 课程封面-->
      <el-form-item label="课程封面">
        <el-upload
          :show-file-list="false"
          :on-success="handleAvatarSuccess"
          :before-upload="beforeAvatarUpload"
          :action="BASE_API+'/eduoss/fileoss'"
          class="avatar-uploader"
        >
          <img :src="courseInfo.cover" />
        </el-upload>
      </el-form-item>

      <el-form-item label="课程价格">
        <el-input-number
          :min="0"
          v-model="courseInfo.price"
          controls-position="right"
          placeholder="免费课程请设置为0元"
        />元
      </el-form-item>
      <el-form-item>
        <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
      </el-form-item>
    </el-form>
  </div>
</template>

<script>
import course from "@/api/edu/course";
import subject from "@/api/edu/subject";
import Tinymce from "@/components/Tinymce";

export default {
  //声明组件
  components: { Tinymce },
  data() {
    return {
      saveBtnDisabled: false,
      courseInfo: {
        subjectId: "", //二级分类id
        description: "", //给简介一个初始值
        cover:
          "https://edu-1010hh.oss-cn-shenzhen.aliyuncs.com/2020/05/27/8f89f8f1b1cf45818cdb0cef721e6fca轮播图3.jpg"
      },
      BASE_API: process.env.BASE_API,
      teacherList: [],
      subjectOneList: [],
      subjectTwoList: [],
      courseId: ""
    };
  },
  created() {
    //获取路由id值
    if (this.$route.params.id) {
      this.courseId = this.$route.params.id;
      //调用 根据课程id查询 方法
      this.getInfo();
    } else {
      //查询所有讲师
      this.getListTeacher();
      //初始化一级分类
      this.getOneSubject();
    }
  },
  methods: {
    //根据课程id查询
    getInfo() {
      course.getCourseInfoId(this.courseId).then(response => {
        //在courseInfo课程基本信息中，包含一级分类id和二级分类id
        this.courseInfo = response.data.courseInfoVo;
        //查询所有的分类，包含一级和二级。
        subject.getSubjectList().then(response => {
          //获取所有一级分类
          this.subjectOneList = response.data.list;
          //把所有的一级分类数组进行遍历
          for (let i in this.subjectOneList) {
            //比较当前courseInfo里面一级分类id和所有的一级分类id
            if (this.courseInfo.subjectParentId == this.subjectOneList[i].id) {
              //获取此一级分类的所有二级分类并复制给data中的变量
              this.subjectTwoList = this.subjectOneList[i].children;
            }
          }
        });
        //查询所有讲师
        this.getListTeacher();
      });
    },
    //上传封面成功调用的方法
    handleAvatarSuccess(res, file) {
      this.courseInfo.cover = res.data.url;
    },
    //上传之前调用的方法
    beforeAvatarUpload(file) {
      const isJPG = file.type === "image/jpeg";
      const isLt2M = file.size / 1024 / 1024 < 2;

      if (!isJPG) {
        this.$message.error("上传头像图片只能是 JPG 格式!");
      }
      if (!isLt2M) {
        this.$message.error("上传头像图片大小不能超过 2MB!");
      }
      return isJPG && isLt2M;
    },
    //点击一级分类，触发change，显示对应二级分类。
    subjectLevelOneChanged(value) {
      for (let i = 0; i < this.subjectOneList.length; i++) {
        let oneSubject = this.subjectOneList[i];
        if (value === oneSubject.id) {
          this.subjectTwoList = oneSubject.children;

          this.courseInfo.subjectId = ""; //此方法为绑定id赋空值，相当于清空刷新二级下拉框，具体原理应该是框架原因。
          return;
        }
      }
    },

    //查询所有的一级分类
    getOneSubject() {
      subject.getSubjectList().then(response => {
        this.subjectOneList = response.data.list;
      });
    },

    //查询所有讲师
    getListTeacher() {
      course.getListTeacher().then(response => {
        this.teacherList = response.data.items;
      });
    },

    //添加课程
    addCourse() {
      course.addCourseInfo(this.courseInfo).then(response => {
        //提示
        this.$message({
          type: "success",
          message: "添加课程信息成功！"
        });
        //跳转到第二步
        this.$router.push({
          path: "/course/chapter/" + response.data.courseId
        });
      });
    },
    //修改课程
    updateCourse() {
      course.updateCourseInfo(this.courseInfo).then(response => {
        //提示
        this.$message({
          type: "success",
          message: "修改课程信息成功！"
        });
        //跳转到第二步
        this.$router.push({
          path: "/course/chapter/" + this.courseId
        });
      });
    },

    saveOrUpdate() {
      //判断添加还是修改
      if (!this.courseInfo.id) {
        this.addCourse();
      } else {
        this.updateCourse();
      }
    }
  }
};
</script>

<style scoped>
.tinymce-container {
  line-height: 29px;
}
</style>